1. Field of the Invention
The invention relates to a data terminal which is connected to an information processing apparatus such as a server or the like through a communication line and receives data and processes it and to a data processing method, a data processing system, and a memory medium for such a data terminal.
2. Related Background Art
In recent years, a radio public telephone network has been established and the number of users of cellular phones and PHSs has been increasing. The realization of advanced functions of the radio public telephone network, cellular phones, and PHSs is being progressed and they have not only a voice talking function but also a data communicating function. Further, various data distributing services using those cellular phones and PHSs with the data communicating function are being provided.
In the data distributing services, a data terminal corresponding to the service is connected to the cellular phone or PHS and processes are executed. Since the data terminal is used in a portable environment, it is driven by a battery. The data terminal also has a power input terminal as a spare power supply from an AC adapter.
In the conventional data processing system, nothing is considered with respect to the operation stop due to a low-battery voltage of the data terminal. If the battery voltage of the data terminal drops to an operation guarantee level or less, a resetting circuit operates and the operation of the data terminal stops suddenly. On the server side, when a response from the data terminal is not made for a predetermined time interval, it is determined that the data terminal is abnormal, so that a line is disconnected and a distributing process is stopped.
In the conventional data processing system, however, in order to cope with a possibility that the operation of the data terminal stops suddenly, it is necessary to assemble a process for such a case into a program on the server side.
The assembling operation of such a corresponding process makes the program on the server side complicated, stops the server side program at an unexpected timing, or the like, so that there is a fear that the server side program is adversely influenced.
In spite of the fact that the operation of the data terminal is stopped due to the low-battery voltage, the line is held in a connecting state for a period of time until the server determines the abnormality of the data terminal, so that a communication fee is wastefully charged and, further, the communication line is not effectively used.
Further, even in an environment such that an AC adapter is used and an AC power supply can be used, if the operation of the data terminal stops suddenly due to the low-battery voltage, the reception of data has to be retried, the communication fee is wasted, and time is wastefully consumed.
It is, therefore, an object of the invention to provide a data terminal, a data processing method, a data processing system, and a memory medium, in which when a battery voltage of the data terminal drops, a surplus time suitable for continuing communication by exchanging the battery to a new one or switching to an AC adapter can be given to the user without exerting an adverse influence on the server side.
To accomplish the above object, according to the first aspect of the invention, there is provided a data terminal which is connected to an information processing apparatus through a communication line and processes data, comprising: voltage detecting means for detecting a low-power voltage of the data terminal during communication with the information processing apparatus; and standby means for waiting for a predetermined time when the low-power voltage is detected.